(a) The Invention
The invention relates to a sealed cable article and method for sealing the area between two or more cables and between the cables and an enclosure at a location where the cables exit from the enclosure. The invention also relates to a sealed cable end article and method for sealing the exposed end of a cable.
(b) Background Information
At various places in an electrical distribution system, an electrical cable is divided into two or more components, for example, where a branch-off cable is connected to a main cable or where a cable containing three or more cores, is separated into the individual cores. Where one or more cables or cores are divided from the main cable, the cable insulation generally has been removed to permit the jointing of a branch-off cable or breakout of the cable cores. The area where the insulation has been removed must then be reinsulated. In the case of shielded or armored power cables, the shielding and armoring is also removed and must be re-established. This is generally accomplished by installing an enclosure around that region of the cables. The term "breakout" is used in this application to refer to either two or more cables or two or more cores where they separate from a main cable or cables.
Enclosures suitable for this use can be, for example, resin filled joint cases, polymeric sleeves or the like. The location where the individual cables exit from an enclosure, the area between the cables and between the cables or cores and enclosure must be sealed to prevent ingress of moisture. A number of methods have been used to seal breakouts with varying success. A heat shrinkable polymeric boot may be positioned on the breakout using mastic or adhesive to hold the boot in place. Heat shrinkable boots however are costly to manufacture because of their shape and usually require access to the cable conductor ends to slip the boot into the proper position over the breakout area. Adhesives and mastics have been put in the area between the breakout cable core and the main cable (crotch area) to seal but these are difficult to pack into the crotch area without leaving voids resulting in a poor seal and may require heat to cause them to flow and fill the crotch area. The application of heat can damage the conductor covering or the conductor. Tapes of dimensionally stable polymeric material with an adhesive or mastic have been used to wrap the cable breakout area but tend to leak if not properly overlapped.
Shaped articles have been used as sealing elements in a variety of methods. In U.S. Pat. No. 4,438,294 a sealing element of a thermoplastic or plastic material for a cable entrance socket is disclosed. The sealing element seals the area between the sheaths of cables using straight sided or concave articles which surround only a portion of the cable and conductors in the crotch area. No gels are disclosed and the thermoplastic or plastic materials described are substantially non-tacky and rigid.
In Great Britain Patent No. 2,057,202, a polymeric article is described comprising a cylindrical member with a plurality of channels for enclosing a plurality of cables. The articles may seal by being made heat recoverable or may be sealed with an adhesive or mastic. They are described as non-tacky useful to seal, protect and insulate cables. In U.S. Pat. No. 4,298,415 a branch off seal is disclosed comprising a heat recoverable sleeve and one or more clips attached to the sleeve opening to form the sleeve into a desired number of cable conduits.